Bischofite
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Bischofite[1][2] | |
Mineralogical name | Bischofite |
Chemical name | Magnesium chloride hexahydrate |
Trivial name | |
Chemical formula | MgCl2•6H2O |
Other forms | |
Crystal system | monoclinic |
Crystal structure | |
Deliquescence humidity 20°C | 33.1% |
Solubility (g/l) at 20°C | 5.75 mol/kg |
Density (g/cm³) | 1.57 g/cm3 |
Molar volume | 129.6 cm3/mol |
Molar weight | 203.30 g/mol |
Transparency | transparent to translucent |
Cleavage | none |
Crystal habit | |
Twinning | |
Phase transition | |
Chemical behavior | |
Comments | decomposes at 116-118°C hygroscopic and deliquescent |
Crystal Optics | |
Refractive Indices | nx =1.495 ny = 1.509 nz = 1.528 |
Birefringence | Δ = 0.003 |
Optical Orientation | positive |
Pleochroism | |
Dispersion | 79° |
Used Literature | |
[Broul.etal:1981]Author: Broul M., Nyvlt J.; Soehnel O. Editor: Elsevier Publisher: Elsevier Title: Solubility in organic two component systems Year: 1981 ![]() Edition: 7 Editor: Dana E.S. Publisher: Wiley & Sons Title: Dana's System of Mineralogy Volume: 2 Year: 1951 ![]() Journal: Geochimica et Cosmochimica Act Number: 12 Pages: 3600-3626 Title: Decomposition reactions of magnesium sulfate hydrates and phase equilibria in the MgSO4-H2O and Na+-Mg2+-Cl--SO42--H2O systems with implications for Mars Volume: 75 Year: 2011 ![]() |
Solubility
Bischofite has got a high solubility in water (5.75 mol/kg at 20 °C). The solubility of bischofite and other phases of the system MgCl2-H2O is shown in Fig. 1.
Hygroscopicity
Figure 2 includes the phase diagram of the system MgCl2-H2O. Next to the hexahydrate bischofite there are two more stable phases within the regarded temperature range. The octa- and the dodecahydrate are relevant at lower temperatures.
0°C | 10°C | 20°C | 30°C | 40°C | 50°C |
34.1%r.h. | 33.7%r.h. | 33.1%r.h. | 32.4%r.h. | 31.5%r.h. | 30.5%r.h. |
Weblinks
- ↑ http://webmineral.com/data/Bischofite.shtml viewed on 29/07/2010
- ↑ http://www.mindat.org/min-681.html viewed on 29/07/2010
Literature
[Broul.etal:1981] | Elsevier (eds.) Broul M., Nyvlt J.; Soehnel O. (1981): Solubility in organic two component systems, %edition%, Elsevier, %address%, %pages%, %url%, %doi% | ![]() |
[Dana:1951] | Dana E.S. (eds.) Dana J.D. (1951): Dana's System of Mineralogy, 7, Wiley & Sons, %address%, %pages%, %url%, %doi% | ![]() |
[Steiger.etal:2011a] | Steiger, Michael; Linnow, Kirsten; Ehrhardt, Dorothee; Rohde, Mandy (2011): Decomposition reactions of magnesium sulfate hydrates and phase equilibria in the MgSO4-H2O and Na+-Mg2+-Cl--SO42--H2O systems with implications for Mars. Geochimica et Cosmochimica Act, 75 (12), 3600-3626, %url%, 10.1016/j.gca.2011.03.038, | ![]() |
[Steiger.etal:2014] | Steiger, Michael; Charola A. Elena; Sterflinger, Katja (2014): Weathering and Deterioration. In: Siegesmund S.; Snethlage R. (eds.): Stone in Architecture, Springer Verlag Berlin Heidelberg, 223-316, %url%, 10.1007/978-3-642-45155-3_4 | ![]() |